1. Field of the Invention
This invention relates to wells and their operation through artificial lift practices, and more particularly, relates to gas lift wells and equipment and methods relating thereto.
2. Background Art
Packoff anchors have been used for many years for sealing or bridging across an opening such as a port (for instance, a perforation, a flow port of a sliding sleeve valve, a leak, or the like) in the wall of well tubing and still permit the flow of well production fluids to the surface through the tubing.
A packoff anchor installation generally includes a stop which is releasably locked or otherwise secured in the well tubing just below the hole to be bridged or sealed off, a packoff anchor which is generally a spacer pipe of suitable length having seal means at its opposite ends which, when the packoff anchor is supported on the stop, seal with the inner wall of the tubing both above and below the hole. Thus, the packoff anchor bridges across or isolates the holes and prevents the flow of fluids between the tubing and the exterior thereof.
Often the packoff anchor has means on its lower end for latching onto the stop to help hold it anchored in place. Since packoff anchors tend to be forced to the surface during production of the well, it is common practice to place a second stop against its upper end to positively secure it in place and, thus, prevent such occurrence.
The following U. S. Patents are familiar to the applicants and each one possibly has some pertinence relative to the invention claimed herein.
______________________________________ 2,393,404 2,687,775 3,215,208 3,278,192 4,333,527 ______________________________________
U.S. Pat. No. 2,393,404 issued Jan. 22, 1946 to Herbert C. Otis and discloses methods and means for placing a well on "gas lift" without disturbing the well tubing by setting a stop in the well tubing, supporting a perforator on the stop, perforating the wall of the tubing a short distance above the stop, removing the perforator, and then installing a removable packoff anchor having one or more orifices in its wall between its upper and lower seals which sealingly engage the tubing above and below the perforation. These orifices control the admission of lift gas into the well flow stream, this lift gas flowing from the annulus into the tubing through the perforation and then through the one or more orifices into the production fluids to aid in lifting such fluids to the surface. The packoff anchor is retrievable from the well with wire line and suitable retrieving tools.
U.S. Pat. No. 2,393,404 also teaches the use of a circulating plug for setting on top of the tubing stop prior to perforating so that, after the perforation has been made, water or other cleaning fluid can be circulated down the tubing, through the perforation, and up the annulus to the surface to clear the annulus of mud, or the like, preparatory to injecting lift gas into the annulus at the surface. The circulating plug will not allow such cleaning fluids to flow downwardly beyond it but forces such fluids to exit the tubing through the perforation into the annulus for its return trip to the surface.
U.S. Pat. No. 3,215,208 issued to Jack W. Tamplen on Nov. 2, 1965 and discloses the use of a gas lift valve in a retrievable packoff anchor. The gas lift valve illustrated is of the concentric type and serves as the spacer for spacing the upper and lower seals. The elements and seal devices of the packoff anchor are essentially the same as those used on one embodiment of the present invention. The gas lift valve may be retrieved only by retrieving the packoff anchor.
U.S. Pat. No. 3,278,192 which issued to Jack W. Tamplen on Oct. 11, 1966 teaches sealing elements for packoff anchors, and the like equipment, such as disclosed in U. S. Pat. No. 3,215,208.
U.S. Pat. No. 2,687,775 issued on Aug. 31, 1954 to Reuben C. Baker. This patent discloses a downhole setting tool for well packers, which setting tool is powered by gas generated by a powder charge therein detonated from the surface by electricity. The pressure of the gas acts through a piston/cylinder to apply opposing axial forces of considerable magnitude to a downhole tool such as a well packer. Such tools are commonly known as setting guns and may be used to set tools other than well packers.
U.S. Pat. No. 4,333,527 issued June 8, 1982 to Robert S. Higgins and David T. Merritt. This patent discloses an improved side pocket mandrel. The side pocket mandrel of this patent is but one of many side pocket mandrels which could be used in practicing the present invention.
U.S. Pat. Nos. 2,393,404; 2,687,775; 3,215,208; 3,278,192; and 4,333,527 are hereby incorporated herein by reference thereto for all purposes.
None of the prior art patents with which the inventors are familiar teaches a side pocket mandrel installed wholly within the bore of a well tubing or one forming a part of a packoff anchor within a well tubing. Neither are the inventors aware of any teaching in the prior art which relates to use of a removable flow control device installed within the bore of a packoff anchor body.